Track-laying vehicles of the kind which, in response to the manipulation of a steering device, are steered for straight ahead movement or for movement to the left or to the right, by moving the tracks at mutually the same speed or at mutually different speeds in relation to the body of the vehicle have long been known in the art. Normally, such track-laying vehicles are provided with clutch and brake devices which are capable of effecting variable power transmission and braking effect between a drive motor and the left or right track respectively, and the vehicle body. Perhaps the simplest method of accomplishing a right or a left turn with such vehicles is to completely disengage the right or the left track respectively from the drive motor, while at the same time applying a heavy braking action through the vehicle braking system. Such two-and-fro steering is relatively jerky and, in some cases, not particularly suitable.
It is known, for instance, from JP No. 56-75977 and U.S. Pat. No. 3,727,710, for the purpose of steering vehicles of this kind to detect the speeds of the right and left wheels or tracks, and to compare the detected speeds with a desired steering effect. The clutch or brakes of the vehicle are then controlled in a manner dependent on the result obtained by the comparison, in order to establish between the right and left wheels or tracks a speed differential which correpsonds to the steering desired.
When steering a vehicle of this kind it is difficult to utilize the ground friction to an optimum extent and, at the same time, to establish continuously variable steering which can be changed and adjusted readily in accordance with the characteristics of the vehicle and the nature of the ground on which the vehicle is driven. Another problem is one of utilizing both clutch and brake devices of the vehicle in an optimal manner for steering purposes.